Non-Gaussianities in two-field inflation

By F. Vernizzi, D. Wands. 2006

313 citations recorded by the source corpus.

We study the bispectrum of the curvature perturbation on uniform energy density hypersurfaces in models of inflation with two scalar fields evolving simultaneously. In the case of a separable potential, it is possible to compute the curvature perturbation up to second order in the perturbations, generated on large scales due to the presence of non-adiabatic perturbations, by employing the δN-formalism, in the slow-roll approximation. In this case, we provide an analytic formula for the nonlinear parameter fNL. We apply this formula to double inflation with two massive fields, showing that it does not generate significant non-Gaussianity; the nonlinear parameter at the end of inflation is slow-roll suppressed. Finally, we develop a numerical method for generic two-field models of inflation, which allows us to go beyond the slow-roll approximation and confirms our analytic results for double inflation.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/a811ff0416098de3bd4c280dd3a692bdb4b7c4b0

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Citations in the corpus

Planck 2015 results. XVII. Constraints on primordial non-Gaussianity (2015, unknown): “…and specific realizations of this transfer mechanism from isocurvature to adiabatic perturbations (Bartolo et al. 2002; Bernardeau & Uzan 2002; Vernizzi & Wands 2006; Rigopoulos et al. 2006, 2007; Lyth & Rodriguez 2005; Tzavara & van Tent 2011; for a review on NG from multiple-field inflation…”
Quasi-Single Field Inflation and Non-Gaussianities (2009, result): “This is in accordance with the general findings of previous studies that it is very difficult to generate large non-Gaussianities in terms of turning trajectories in multifield slow-roll models [22], essentially because imposing slow-roll conditions in all directions are very restrictive.”
Review of local non-Gaussianity from multi-field inflation (2010, methodology): “The numerical calculation confirms the analytical prediction that it is possible to generate a narrow spike of large non-Gaussianity while the inflaton trajectory turns a corner, but the non-Gaussianity decays quickly after the corner [99, 100].”
Non-linear isocurvature perturbations and non-Gaussianities (2008, methodology): “The adiabatic curvature perturbations generated by this model have been computed in [11, 38, 39] and their non-Gaussianity in [40, 41, 42] (see also [43]).”
Effective theories of single field inflation when heavy fields matter (2012, unknown): “[36–39].”
Non-Gaussianities in multi-field inflation (2006, methodology): “This formalism was proposed by Starobinsky [19] and further developed by Sasaki and Stewart in [20], and others in [16, 17, 21].”
Cosmology and Fundamental Physics with the Euclid Satellite (2012, background): “In this case, the overall expansion of the universe is affected by each of the field while it is in slow-roll; thus, the final non-Gaussianity is slow-roll suppressed, as in single field inflation (Rigopoulos et al. 2006; Alabidi and Lyth 2006; Vernizzi and Wands 2006).”
The effective field theory of multifield inflation (2010, methodology): “Some related earlier papers that focused on non-Gaussian 3-point and 4-point functions are for example [19, 20, 21, 22, 23, 24, 25].”
Primordial Non-Gaussianity and Bispectrum Measurements in the Cosmic Microwave Background and Large-Scale Structure (2010, background): “…during multiple field inflation (Bernardeau & Uzan, 2003, 2002; Lyth & Rodriguez, 2005; Rigopoulos et al., 2006a,b, 2007; Seery & Lidsey, 2005; Vernizzi & Wands, 2006) shows much greater promise through conversion of isocurvature into adiabatic perturbations (see, for example, recent work in…”
Shape of primordial non-Gaussianity and the CMB bispectrum (2008, background): “Here non-Gaussianity is created by the inflaton when it follows a curved trajectory in phase space, during which isocurvature perturbations are converted into adiabatic perturbations [35, 36].”
Planck 2018 results. IX. Constraints on primordial non-Gaussianity (2019, background): “This, along with nonlinearities in the transfer mechanism itself, is a potential source of significant NG (Bartolo et al. 2002; Bernardeau & Uzan 2002; Vernizzi & Wands 2006; Rigopoulos et al. 2006, 2007; Lyth & Rodriguez 2005; Tzavara & van Tent 2011; Jung & van Tent 2017).”